A water or gas main is connected to a building, such as a residential house, via a service line which extends from the main to the building below the frost line. The service line is provided with a service line shut-off valve assembly, typically near the curb. In order to turn the water or gas supply to the structure either "on" or "off" a valve service box is provided. The valve service box has a service valve housing disposed about the shut-off valve assembly, a cover, and a tubular structure which extends between the cover and the service valve housing. When the cover is removed, a conventional rod key may be passed through the tubular structure and the service valve housing for turning the water or gas supply "on" or "off".
A common form of service box in use today has top and bottom cast iron sections. The bottom section includes a service valve housing and an integral upwardly extending cylindrical portion provided with external threads. The top cast iron section includes a cylindrical housing having an outwardly extending flange near its top upon which may rest a downwardly extending flange of a metal cover, the cover being secured to the top section by a suitable fastener in the form of a bolt which passes through an aperture in the top and which is screwed into an inwardly extending flange portion on the top section. The lower portion of the cylindrical housing of the top section is provided with internal threads which may cooperate with the threads on the bottom section so that the overall length of the service box may be varied. While this form of service box is widely accepted, it requires the installer of service boxes to have a number of differing sizes in stock as the service pipe shut-off valve assemblies may be disposed at varying distances below ground surface. Thus, one manufacturer provides four different lengths of bottom sections and three different lengths of top sections. Representative examples of cast iron service boxes are shown in U.S. Pat. Nos. 407,955 and 2,099,479.
While cast iron devices hold up quite well in use, they have the disadvantage in that they are relatively heavy and are subject to corrosion. To this end it has been proposed to form valve service boxes of material other than cast iron. Examples are shown in U.S. Pat. Nos. 3,746,034 and 4,691,733. In these patents the telescoping screw adjusted top and bottom cylindrical sections are formed of a suitable non-metallic material, such as polyethylene. While these patents also use threaded top and bottom sections, it is well know that other means may be employed for adjusting the length between the top cover and the bottom bell housing. U.S. Pat. No. 2,931,383 shows a valve service box formed of a non-metallic material such as cellulose, acetate, butyrate, acrylonitrile, a rubber molding compound, or the like. This valve service box includes as its principal components an upper tubular section telescoped within a lower tubular section, and a bell housing which is cemented to the lower end of the lower tubular section. The upper and lower tubular sections are secured to each other by a set screw or the like. A more recent patent to the same inventor is U.S. Pat. No. 3,548,864 which discloses a somewhat similar structure. However, the lower tubular section and the bell housing are formed as single integral piece, and the upper tubular section is telescoped within the lower tubular section and is held from longitudinal movement by friction means.
While some of the more recent patents overcome the disadvantages of corrosion and the weight of a cast iron valve service boxes, they still have the disadvantage of requiring a number of upper and lower telescoping tubular members of different lengths in order to meet differing length requirements. This requires the installer to have a larger inventory of parts than would be necessary than with the present invention.